Fluid pressure motor



8, 1959 R. A. GIBBS ETAL 2,899,940

FLUID PRESSURE MOTOR 2 Sheets-Sheet l I I I Filed May 3. 1954 INVENTOR5 ROBERT A. GIBBS THOMAS A. GIBBS ROBERT LAURIE BRINSON BY W ATTORNEY Aug. 18, 1959 R. A. GIBBS ET AL FLUID PRESSURE MOTOR Filed May 3, 1954 2 Sheets-Sheet 2 INVENTORTJ ROBERT A. GIBBS THOMAS A; GIBBS ROBERT LAURIE BRINSON ATTORNEY United States Patent FLUID PRESSURE MOTOR Robert A. Gibbs, Greensboro, and Thomas A. Gibbs and Robert Laurie Brinson, High Point, N .C.

Application May 3, 1954, Serial No. 427,306

2 Claims. (Cl. 121-86) This invention relates to fluid pressure motors, such as compressed air motors, for example. The fluid pressure motor of the invention may be used as a starting motor for an internal combustion engine but is not restricted to such use.

It is an object of this invention to provide an improved fluid pressure motor adapted to be driven by compressed air or the like and which is eflicient in operation and capable of heavy duty service.

It is a further object of this invention to provide a fluid pressure motor which the drive vanes of the rotor member are maintained effectively sealed with the surface of the chambers in which they move to prevent leakage of air pressure and consequent loss of power in the motor.

It is a further object of this invention to provide a fluid pressure motor having an improved means for maintaining the vanes of the motor in sealed engagement during their movement.

It is still another object of this invention to provide a fluid pressure motor adapted to be driven by compressed air or the like and which is particularly suitable for use as a starting motor for heavy duty automotive vehicles such as those having diesel and heavy duty gas engines.

In achievement of these objectives, there is provided in accordance with this invention a fluid pressure motor particularly adapted to be driven by compressed air and including a housing having a central axially extending bore and two additional axially extending bores in offset relation to the first bore but merging therewith. A rotor member is mounted for rotation within the central bore and is provided with a plurality of circumferentially spaced longitudinally extending vanes which are received in radial slots in the rotor. The outer surface of the rotor cooperates with the two oppositely disposed offset bores of the housing to provide two oppositely disposed crescent-shaped chambers through which the rotor vanes rotate. High pressure air is admitted to the trailing edge of the vanes as they move into the crescent-shaped chambers, the engagement of the high pressure air with the surface of the vanes causing the rotary movement of the rotor member.

An important feature of the construction is the use of a biasing spring adjacent the underneath edge of each vane member to bias the vane radially outwardly into sealing engagement with the surfaces of the bores. Cooperating with the biasing springs to project the vane members radially outwardly are bleeder passages in the end plates of the motor through which compressed air is admitted to the radially inner portions of the vane-receiving slots and beneath the radially inner edges of the respective vanes in such manner as to assist the spring members to bias the vanes into sealing engagement with the surface of the crescent-shaped chambers.

Further objects and advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawings in which:

Patented Aug. 18, 1959 Figure 1 is a schematic view of the pneumatic system for supplying fluid pressure, such as compressed air, to the fluid pressure motor;

Figure 2 is a view in transverse section of the fluid pressure motor;

Figure 3 is a view in side elevation of the motor and partially in longitudinal section along line 3-3 of Figure 2;

Figure 4 is a view in section along line 44 of Figure 3; and

Figure 5 is a perspective view of one of the vane members of the fluid pressure motor with its biasing spring.

Referring now to the drawings, there is shown in Figure 1 the general orientation of the fluid pressure motor of the invention with respect to the pneumatic system of a heavy duty automotive vehicle, such as one having a diesel or heavy duty gas engine, when the fluid pressure motor is used as a starting motor for the engine. The fluid pressure motor is generally indicated at 10 and is connectable in driving engagement to the heavy duty internal combustion engine 12 in the usual manner to serve as a starting motor for engine 12. The compressed air which drives fluid pressure motor 10 is obtained from a supply tank 14 which is connected through conduit 16 in series with cut-off valve 18 and control valve 20 to the inlet end of fluid pressure motor 10. An air compressor 22 is driven by internal combustion engine 12 and is connected through conduit 24 to brake tanks 26 and 28 and through conduits 24 and 30 to air supply tank 14 for the starting motor. When the internal combustion engine is in operation, it drives air compressor 22 to store air in supply tank 14, this air thenbeing available to operate fluid pressure motor 10 when internal combustion engine 12 is being started.

The fluid pressure motor 10 includes a housing having a longitudinally extending main body portion indicated at 32 which is of generally cylindrical shape on its exterior. Body portion 32 has a hollow chamber on its interior formed of three merging circular bores, 34, 36, 38 each having a different center. Bore 34 is concentric with the outside diameter of the housing while the other two bores have their respective centers offset on opposite sides of the true center of the housing by a predetermined disstance, such as inch, for example.

A rotor member 40 is supported for rotation within the central bore about an axis passing through the true center of the housing so that the outer surface of the rotor is substantially tangent to the central bore 34 but is spaced from the offset bores 36 and 38 in such manner as to form crescent-shaped chambers indicated at 42 and 44, respectively.

As will best be seen in Figure 3, the housing 32 includes at its rear or right-hand end, with respect to the view shown in the drawing, a rear end plate 46 which is rigidly secured to the main body portion 32 as by screws 48. Rotor 40 is supported for rotation at its rear end by means of a ball bearing 50 whose outer race is supported by rear end plate 46. At the front end of the fluid pressure motor, a front end plate 52 is rigidly connected to the forward end of the body portion 32 and sup ports a ball bearing 54 which in turn supports the forward end of the shaft of rotor 40. Front end plate 52 in turn is secured to drive shaft housing 56. A pinion 58 carried by the forward end of the rotor shaft projects into drive shaft housing 56 where the power output of fluid pressure motor 10 is available for starting the in ternal combustion engine 12.

At its rear end, the fluid pressure motor is provided with an end cover 60 which is rigidly secured by means of bolts 48 to rear end plate 46 and to the main body portion 32 of the fluid motor housing.

End cover 60 is provided with an inlet opening 62 which is connected to the source of high pressure air, such as air supply tank 14, shown in Figure 1. End cover 64) is hollow on its interior and is spaced from the outer periphery of rear end plate 46 to define an inlet passage 64. Inlet opening 62 and inlet passage 64 communicate with a pair of longitudinally extending diametrically opposite air inlet passages 66 and 68, respectively, provided in the radially outer part of main body portion 32. Inlet passages 66 and 68 extend for the entire'length of main body portion 32. Rear end plate 46 has a pair of dia metrically opposite openings 69 and 71 (Figure 4) which provide communication between inlet-passage 64 and the longitudinally extending inlet passages 66 and 68.

Inlet passages 66 and 68, respectively, communicate with the crescent-shaped chambers 42 and 44 just slightly past the point where the rotor vanes enter the respective crescent-shaped chambers. In order to provide communication between the respective inlet passages 66 and 68 and the crescent-shaped chambers 42 and 44, the wall of the housing has a plurality of spaced radial passages such as those indicated at 70 in Figure 3 which extend between each passage 66 and 68 and the respective crescentshaped chambers 42 and 44.

Rotor 40 is provided with a plurality of circumferentially spaced radially extending slots 72 and in each of these slots is positioned a vane 74 made of any suitable material, such as a fibrous material, for example. As will best be seen in Figures 3 and 5, each of the vanes 74 has attached to its inner edge adjacent the inner end of slot 72 an arcuate biasing spring 76 which is pivoted at one end at 78 to the underneath or radially inner edge of vane 74 and which is free at its opposite end to slide on the beveled end surface 77 of the vane. The fixed end of spring 76 has a circular loop which is pivotally received in a correspondingly-shaped slot in vane 74. When vanes 74 are positioned in rotor slots 72 as shown in Figure 2, spring 76 tends to urge the vanes radially outwardly into engagement with the inner surface of the respective bores 34, 36 and 38.

A pair of oppositely disposed exhaust passages 80 and 82 extend longitudinally on diametrically opposite sides of the motor housing, being formed inlongitudinal projections which extend radially beyond the remainder of the housing or body portion 32. Passages 80 and 82 respectively communicate with the crescent-shaped chambers 42 and 44 adjacent but arcuately spaced slightly from the end of the respective crescent-shaped chambers in the counterclockwise direction of travel of the rotor. Exhaust passages 80 and 82 communicate with crescent-shaped chambers 42 and 44 by means of longitudinally spaced slots such as those indicated at 83 in Figure 3.

An important feature of the invention is the use of pneumatic pressure to assist the spring members 76 to bias vanes 74 into tight sealing engagement with the inner surface of the bores 36 and 38 of crescent-shaped chambers 42 and 44 to thereby prevent loss of pressure and consequent inefficient operation of the motor.

As will best be seen in Figures 3 and 4, the rear end plate 46 is provided at its upper portion with a pair of bleeder passages 84 which communicate with the inlet passage 64 in advance of opening 69 in end plate 46 which connects inlet passage 64 with longitudinal inlet passage 60. In a similar manner, at the lower end of rear end plate 46, bleeder passages 86 communicate with the lower end of inlet passage 64 in advance of opening 71 in the end plate which communicates with longitudinally extending inlet passage 68.

At their radially inner end, the upper bleeder passages 84 communicate with an arcuately extending opening 88 in rear end plate 46. Arcuate opening 88 is disposed at a radial position which corresponds to the lower ends of the slots 72 which receive vanes 74. Thus, the bleeder pressure through radially extending passages 84 is communicated through arcuate opening 88 to the lower ends of slots 72. The location and length of the arcuate opening 88 is such that a slot 72 of a vane just passing into the crescent-shaped chamber 42 is placed in communication with the bleeder pressure and is maintained in communication with the lower end of slot 72 until the respective vane reaches the exhaust opening 80.

In a similar manner, bleeder passages 86 at the lower end of rear end plate 46 communicate with an arcuately extending slot 90 in rear end plate 46. The direction and length of arcuate slot 90 is such as to maintain bleeder pressure in communication with the lower end of slot 72 of each vane from the time that it enters the crescent-shaped chamber 44 until the respective vane has reached the exhaust opening 82.

In order to assure a uniform pneumatic pressure at the underneath edge of each of the respective vanes 74 for the entire length of the vane, provision is made to admit bleeder pressure to the lower end of each slot 72 beneath the vane 74 at the front or forward portion of the motor in the same manner as just described at the rear portion of motor. This is achieved by radially extending bleeder passages such as those indicated at 92 in the front plate 52 of the motor. Bleeder passages 92 communicate at their radially outer end with inlet passage 66 and at their radially inner end with an arcuate slot 94 similar to the arcuate slots 88 and 90 previously described. A similar bleeder passage and arcuate slot arrangement communicating with longitudinal inlet passage 68 is provided at the lower end of the motor. The bleeder passage constructed at the forward end of the motor will not be described in detail since it is similar to that already described for the rear end of the motor.

In the operation of the motor hereinbefore described, high pressure air is admitted through inlet opening 62 and passes through the inlet passage 64 which communicates with the longitudinally extending inlet passages 66 and 68. The high pressure air passes through the radially v extending slots 70 from the respective inlet passages 66 and 68 and into engagement with the trailing'edge of a vane 74 just entering one of the respective crescent-shaped chambers 42 or 44. Due to the substantially tangential engagement of the outer surface of the rotor with the central bore portion 34, leakage of the inlet pressure air at the trailing end of the respective crescent-shaped chambers, with respect to the direction of rotation is prevented.

The pressure of biasing spring 76 tends to force each vane 74 radially outwardly into engagement with the surface of the respective bore portions 36 and 38 as the vanes move into the crescent-shaped chambers. The biasing pressure of spring 76 is aided by the high pressure air which passes from inlet passage 64 through the radially extending bleeder passages 84 and 86 and through the arcuate slots 88 and 90 into the radially inner end of the respective slots 72. The high pressure air at the radially inner edge of the vane causes the vane to be forced radially outwardly into tight sealing engagement with the surface of the bore 36 or 38. Similar bleeder passages 92 at the front end of the motor in the front end plate 52 permit high pressure air to pass into the radially inner portions of slots 72 from the forward end of the slots.

The force of the main flow of high pressure air behind the trailing edge of each of the vanes forces the vane in a counter-clockwise direction with respect to the view shown in Figure 2, thereby imparting rotation to rotor 48. As each vane reaches exhaust outlet 88 or 82, the high pressure air behind the trailing edge of the respective vanes passes outwardly to exhaust. In the meantime, before the vane which is completing its movement through the crescent-shaped chamber has reached the exhaust .opening, another vane begins to move into place at the beginning of the crescent-shaped chamber to prevent any direct communication between the inlet conduit 66 and the exhaust outlet or between the inlet conduit 68 and the exhaust conduit 82.

It can be seen from the foregoing that there is provided in accordance with this invention an improved fluid pressure motor which is elficient in operation and which has an improved sealing means for preventing leakage of high pressure air past the rotor vanes of the motor. The combined action of the spring biasing pressure on the vanes plus the pneumatic biasing pressure introduced into the rotor slots adjacent the underneath edge of the vanes maintains the radially outer edges of the vanes in tight sealing relation to the oflset bores to prevent any leakage of pressure past the vanes. The fluid pressure motor of the invention is particularly suitable for use in starting heavy duty internal combustion engines, such as diesel engines or heavy duty gas engines.

While there has been shown and described a particular embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention and, therefore, it is aimed to cover all such changes and modifications as fall within the true spirit and scope of the invention.

Having thus fully described our invention, what is claimed is:

1. A fluid motor comprising a housing having a bore therein, a rotor rotatably mounted in said bore on an axis offset with respect to said bore, said rotor being providedwith a plurality of radially extending slots, a plurality of blades mounted in said slots, a relatively flat elongated leaf spring of approximately the width of a slot mounted in each slot and urging the cooperating blade outwardly, means to detachably secure one end of said spring to its associated blade, the other end of said spring reacting against said blade and an intermediate portion of said spring reacting against the bottom of the slot whereby the blades are biased to project against the housing, each blade being provided with a transverse substantially circular bore opening along its periphery into the inner edge of the blade, the leaf spring being provided with a curved end adapted to be pivotally received in the circular bore with the leaf spring projecting from the peripheral opening in said bore and permitting flexure of the leaf spring without localized stress.

2. The invention according to claim 1 in which the outer ends of the inner edge of the blade are tapered.

References Cited in the file of this patent UNITED STATES PATENTS Ferris Mar. 24. 1953 

